Absorbent articles such as diapers, training pants, incontinence products, feminine hygiene products, swim undergarments, bed pads, and the like conventionally include a liquid permeable body-side liner, a liquid impermeable outer cover, and an absorbent core. The absorbent core is typically located in between the outer cover and the liner for taking in and retaining urine, bowel movements, and other body exudates exuded by the wearer.
The absorbent core can be made of, for instance, superabsorbent particles. Many absorbent articles, especially those sold under the tradename HUGGIES™ by the Kimberly-Clark Corporation, are so efficient at absorbing liquids that it is sometimes difficult to tell whether or not the absorbent article has been insulted with a body exudate such as urine or bowel movement.
Accordingly, various types of moisture, wetness or bowel movement indicators have been suggested for use in absorbent articles in order to detect the presence of a urine or bowel movement insult within an absorbent article. These indicators may include alarm devices that are designed to assist parents or care-givers identify a wet or soiled diaper condition early on. The devices produce either a visual or an audible signal.
In some embodiments, a wetness indicator has been added to an absorbent article to detect urine insults, and in other embodiments, a sensor for odor detection has been added to detect bowel movement insults. In these embodiments, sensors using conductive materials are incorporated into the absorbent article where the urine insult or bowel movement insult must come into close contact with the sensing elements in order for the indicator to detect an insult. For example, the conductive materials serve as conductive leads for a signaling device and form an open circuit in the article that can be closed when a body fluid, such as urine, closes the circuit. In these embodiments, although the absorbent articles may be disposable, the signaling devices are not. Thus, the signaling devices are intended to be removed from the article and reattached to a subsequent article.
Problems, however, have been encountered in designing an absorbent article with conductive materials where the urine or bowel movement comes into sufficient contact with the conductive materials to close the open circuit. Further, problems have been experienced in including conductive materials such as metals within an absorbent article because such materials trigger metal detectors during the shipping process. Additionally, the use of conductive leads makes it difficult for manufacturers of absorbent articles to monitor their products from a safety standpoint. For example, it may be difficult to ensure consumers that a product is free of all other metals or other foreign objects with the exception of the conductive leads. Therefore, a need exists for an absorbent article that can detect both urine and bowel movement insults without the use of conductive leads.
Additionally, advances in absorbent article technology with the use of hydrophobic inner layer in absorbent articles permits urine to pass through the surface of the absorbent article so that it cannot come in contact with the skin, even after multiple insults. However, feces or bowel movements cannot be absorbed completely into any of these layers, meaning that prolonged contact with skin is inevitable. An electronic device that can detect body fluids such as urine and bowel movement components is highly desired, particularly for new users as well as users of adult care incontinent products. Since several of the prior arts to detect the presence of bowel movements are based on wetness sensing, they fail to discriminate between urine and bowel movements. This could mislead a user and adds an additional burden to an already overloaded caregiver. One of the challenges of the marketed indicators is that it cannot discriminate between bowel movement, sweat and passing gases. A sensor that can discriminate between urine and bowel movement would allow for a caregiver to react more quickly to changing an absorbent containing a bowel movement insult, where prolonged contact of the insult with the child's skin can be detrimental to the child's health.